1. Field of the Invention
The present invention relates to an antilock brake control system including wheel speed detecting means for detecting a wheel speed, a vehicle speed presuming means for detecting a vehicle speed based on the wheel speed detected by the wheel speed detecting means, a slip rate calculating means for calculating a slip rate based on the wheel speed detected by the wheel speed detecting means and the presumed vehicle speed determined in the vehicle speed presuming means, a target slip rate determining means for determining a target slip rate based on the presumed vehicle speed determined in the vehicle speed presuming means, a deviation calculating means for calculating a deviation between the target slip rate determined in the target slip rate determining means and the slip rate calculated in the slip rate calculating means, and a PID calculating means for carrying out a PID calculation based on the deviation determined in the deviation calculating means, wherein the operation of braking liquid pressure regulating means is controlled based on the result of a calculation in the PID calculating means.
2. Description of the Related Art
Such a control system is conventionally known, for example, from Japanese Patent Application Laid-open Nos.6-144195 and 7-117653.
In the above known control system in which the control of a braking pressure is carried out based on a PID calculation, however, there is a possibility that the PID calculation value may become too large due to an alteration of data caused by an unexpected phenomenon such as the generation of a noise around a calculating system. If the control of the braking pressure is continued based on such excessively large PID calculation value, there is a possibility that a difference between the wheel-slipping state presumed in the calculation system and an actual wheel- slipping state may be increased, and when a sudden variation is thereafter produced in the wheel slipping state due to a variation in friction coefficient of a road surface or the like, a delay may be produced in the control of the braking pressure, resulting in a degraded control followability.